1. Field of the Invention
The invention relates to an electrode lead for implantation into a small heart vessel, especially into e.g. the coronary sinus, comprising an elongated outer insulating lead body having a proximal end, a distal end and at least one electrode pole at the distal end, further comprising at least one electrical conductor unit for said electrode pole, each of said electrical conductor units having a conductor core and a separate insulating sheath surrounding said conductor core, and a lumen in the insulating body.
2. Description of the Related Art
Electrode leads of the above type are well known from the prior art. They serve as an electrical connection between an electrotherapeutic implantable device, which may be e.g. a pacemaker, and the location being treated in the body. By means of the electrode pole at the distal end of the lead e.g. a stimulation pulse can be applied to the cardiac tissue or electrical heart signals can be measured. When such an electrode lead is to be implanted in small heart vessels, like coronary venous vessels, there rise specific problems which are to be discussed as follows:
When the vessel scheduled to accommodate the electrode lead is too small another vessel must be found the dimensions of which are sufficient to receive the lead. If this is not possible the implantation procedure must be abandoned in favour of surgical implantation of e.g. an epicardial lead.
When the electrode lead is too difficult to handle or the placement of the lead is sophisticated or even impossible this again might give reason to epicardial lead surgery or an inadequate placement of the electrode lead. The latter results in an insufficient or at least suboptimal therapeutic performance as concerns e.g. resynchronization.
Basically known electrode leads comprise a steering mechanism with at least one pull wire running in a lumen of the lead body. By pulling this wire at the proximal end of the lead body the distal end can be bended. Thus by rotating the lead body around its longitudinal axis the distal tip of the lead body can be controlled in his position and direction and thus can be fed into a small vessel at a vein branch.
It is a matter of fact that this steering mechanism demands a certain space within the sectional contour of the lead body which is contrary to the requirement of miniaturizing the electrode lead to facilitate the placement in small heart vessels.